This invention relates in general to aerosol dispensing apparatus. In particular, this invention relates to an improved aerosol dispensing apparatus having either a metering valve or a flow control valve in combination with an electronically actuated microvalve and configured for use in dispensing aerosol formulations.
A conventional aerosol dispensing apparatus may have a metering valve that provides a means by which aerosols are dispensed from an attached aerosol container. Such metering valves are useful for administering medicinal formulations to a patient in aerosol form.
When administering medicinal formulations, a dose of the medicinal formulation sufficient to produce a desired physiological response is delivered to the patient. It is important that a predetermined amount of the medicinal formulation be dispensed to the patient in each successive dose. Therefore, any dispensing system must be able to dispense doses of the medicinal formulation accurately and reliably.
A metering valve may be used in an aerosol dispensing apparatus, such as a metered dose inhaler, to regulate the volume of a medicinal formulation passing from an aerosol container to a metering chamber. The metering chamber defines the maximum amount of the medicinal formulation that will be dispensed as a dose to the patient. Many aerosol dispensing apparatus rely on a controllable flow of the medicinal formulation into the metering chamber to control the accuracy and/or precision of successive metered doses of the medicinal formulation. The flow of the medicinal formulation through a conventional metering valve may become disrupted however, resulting in inconsistent or inaccurate doses of the medicinal formulation. Thus, it would be desirable to provide an improved structure for an aerosol dispensing apparatus that allows for more precise control of dosages of medicinal formulations in aerosol form.